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javascriptcanvasaspect-ratiotext-size
David
David

Reputation: 1174

JavaScript Canvas Text Ratio

i have a fixed sized Canvas (850x400px) and when I'm adding text to this canvas, its scaled up in a weird way, and I don't know why.

If I do not set the canvas to a specific height/width, the text appears normal, why is that?

export function addText() {
  var canvas = document.getElementById("canvas"); // 850x400px
  var ctx = canvas.getContext("2d");
  var y = 1 * 20 + 20;

  var text = {
    text: "ABC",
    x: 20,
    y: y
  };

  ctx.font = "40px consolas";
  text.width = ctx.measureText(text.text).width;
  text.height = 80;
  ctx.fillText(text.text, text.x, text.y);
}

This is what the text in the canvas field will look like:

enter image description here

How can I insert text that is scaled just like normal 40px font?

Upvotes: 3

Views: 428

Answers (1)

Tamas Szoke
Tamas Szoke

Reputation: 5542

I think you have not specified the width and height of the canvas HTML element itself, try:

addText();

function addText() {
  var canvas = document.getElementById("canvas"); // 850x400px
  var ctx = canvas.getContext("2d");
  var y = 1 * 20 + 20;

  var text = {
    text: "ABC",
    x: 20,
    y: y
  };

  ctx.font = "40px consolas";
  text.width = ctx.measureText(text.text).width;
  text.height = 80;
  ctx.fillText(text.text, text.x, text.y);
}
<canvas id="canvas" width="850" height="400" style="background: red"></canvas>

Update

Another option is to set the width and height programmatically, this will prevent the zooming:

let canvas = document.getElementById("canvas");

canvas.height = window.innerHeight;
canvas.width = window.innerWidth;

I used the window width and height, but any other element will do it.

Upvotes: 2

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